Are blood haemoglobin concentrations a reliable indicator of parasitism and individual condition in New Holland honeyeaters (Phylidonyris novaehollandiae)?

Abstract

Across avian species, total blood haemoglobin concentration (BHC) is the most important determinant of oxygen-carrying capacity, and most accurately reflects the potential for the bird to satisfy its oxygen requirements. This creates a close association between high BHC and high aerobic capacity, and low BHC and states of regenerative or non-regenerative anaemia. As such, total BHC has been suggested to be a reliable indicator of avian health and condition. We mist netted 160 adult and 26 juvenile New Holland honeyeaters (Phylidonyris novaehollandiae) from ten sites across South Australia to assess the relationship between BHC and individual health and condition traits in this species. From each bird we collected samples for blood haemoglobin estimation, inspected for the presence of external parasites (ticks), and measured basic morphometric parameters (mass, tarsus length, and length of bilateral tail feathers). A relationship could not be demonstrated between BHC and tick intensity, body condition or tail feather asymmetry in adult or juvenile birds. While the measurement of BHC may provide a reliable insight into individual health and condition in some avian species, our results highlight the need to validate this relationship within species and populations prior to its use in avian health and condition assessments.